Pressure-fluid-operated tool



April 16, 1929. E H, SHAFF TAL y Y 1,709,159

PRESSURE FLUID OPERATED TooL Filed Nov. 14, 1925 l rllllar.

1521107215715; ,Emma ff. www, CioztLwZfI nqge/L,

Patented Apr. Y 16, 1929.`

UNlTED STATES PATENT GFFICE.

ERNEST E, SHAFF AND GOTTLIEB BRIEGEL, F GRAND HAVEN, MICHIGAN, ASSIGNORS TO WILLIAM H. KELLER, INC., 0F GRAND HAVEN, MICHIGAN, A CORPORATION 0F MICHIGAN.

Application i'led November The invention relates generally to pressure fluid operated tools oi the type embodying a reciprocating piston and moreparticularly to improved means for controlling the admission and exhaust of pressure fluid in Vsuch tool wherein the length of the piston is greater' than the length of the stroke.

It is the general object of the invention to provide in a tool of this type, improved means adapted to obtain arapid reciprocation of the piston and also adapted to permit op eration of the tool at a high elliciency. Y

It is another' object of the invention to provide in such a tool a reciprocating piston for impacting a tool and improved means whereby the piston is adaptedv also to control the tlow of motive fluid to the forward end of the piston chamber'.

Further objects and advantages of the invention vwill be understood from the ollow ing detailed description taken in connection with the accompanying drawings in which:

Figure 1 is a longitudinal view partly in` central section, vofa tool embodying the pre- 'lerred i'orm of the invention. Y

Fig. 2 is a central longitudinal sect-ion iny a plane at an angle to that of Figure 1.

' `Fig. 3 is a fragmentary*viewV in the same plane as Fig. 2, illustrating a modified form of the invention.

rlhe invention in the exemplary form is illustrated as embodied in a pneumatic chipping'hammer comprisingpthe usual barrel 1 and handle 2, the handle being secured to the barrel as by means ot the screw threads 3. Secured between the vrear end of the barrel and an innerwall of the handle is a valve casing comprisinga hollow cylindrical member d closed at its forward end, and an apertured disk shaped member 5 closing the larger portion of the rear end of the member 4. Slidably mounted for reciprocation in said valve casing is a hollow cylindrical valve 6;' Slidably mounted within a piston chamber 7 of the barrel 1 is a piston 8 adapted to impact a tool 9 secured in the forward end or" the barrel in a. well known manner.

.In referringto the drawings it shouldv be understood that in a sense they are diagrammatic for the purpose of moreV clearlybillustrating the invention. Thus various ports and passages are illustrated as lying in the same plane whereas as is well known to those skilled in the art, it is customary in tools of PRESSVREFLUID-OPERATED TOOL.

14, 1925. serial 1ro. 68,984.

this type to position some of the connecting ports and passages in different planes and also to provide a plurality of those passages through which it is necessary to pass large quantities ot the motive fluid in a short interval or time.

In Fig. 1 the valve 6 is `shown in its rear position where it is adapted to uncover an inlet passage to admit pressure iluid to the rearv end of the piston chamber 7 to drive the piston 8 forward, and to uncover an exhaust passage trom the piston chamber forward ot the piston. Referring particularly lto this ligure, a passage 10 in the handle is adapted to communicate with a suitable supply of pressure lluid (not shown). A passage 11 in the handle establishes communication between said passage 10 and aI central passage 12 inthe valve 6. The valve in its rear position uncovers an annular groove 13 in communication with the rear end ot the piston chamber by means ot passages 14; in the valve casing.

The exhaust passage from the forward end et the .piston chamber comprises a por-t 15 leading into one end of a passage 16 which extends longitudinally of the barrel 1 and valve casing member 4 and connects with an annular chamber 17 in the valve casing through a passage 16a. Passages 18 in the valve casing member 4E lead from a portion 17a oit said groove-chamber 17 to an annular chamber 19 formed between the valve casing and the handle L), said chamber being in constant communication with the atmosphere through an exhaust port 20.

In the preferred embodiment illustrated herein, the piston 8 is provided with an annular circumferential groove 21 which is adapted to coact with the wall of 'the piston chamber 7 to form an annular chamber 22. With the piston in its forward position, this annular groove is adapted to establish com munication between ports 23 and 24 in the barrel 1, port 23 being in constant communication with the pressure fluid supply through a passage 25 in the barrel and valve casing leading to a constantly open annular inlet port 26 in the said valve casing. The port 24 by means of a longitudinal passage 27 in the barrel and valve casing, communicates with a chamber 28 formed between the said valve casing and an annular flange 29 on the valve.

ln addition to establishing communi cation between the ports 23 and 24, the groove 21, when the piston is in a forward position, establishes communication between the port 23 and a port 30 in the barrel (Fig. 2) which leads to a passage 31 opening into the forward end of the piston chamber 7 Vt irough a port 32. Thus, when the piston is in this forward position, the annular chamber 22 permits pressure fluid constantly supplied 'the port 23 to be admitted to the forward end of the piston chamber 7. As the exposed area of the fiange 29 on the valve 6 is greater than the v area of the forward end 33 of the valve, and the pressures acting thereon are practically equal with the parts as in y1, the force to thel rear ofthe piston 3 exerted onthe flange 29 is greater than that exerted on the end 33, whereupon the valve is moved forward 'to the position shown inv ber 19 and exhaust ooi-ts 20. As the piston moves rearwardly it closes the ports 23, 24

` and 30 and uncovers ports 34 and 35 in the ba 1rel 1, port 34 being in constant communication with the chamber 19 by means of passage 36, andport 35 leading to passage 27.

In Fig. 3 is illustrated a modified form of the invention, the port 30 and passage 31 of the `form shown in Figs. 1 and V2 being omitted anda passage 37 provided instead, this passage being adapted to establish communication between the annular chamber 22 and the port through the passage 16 when the piston is in its forward position.

lThe operation of the tool is as follows: Pressure iiuid from the passage 10 admitted to the rear endof the pistonchamber.

when the valve is in its rear position as shown in Fie'. 1, through an' inlet passage comprising the passage 11, passage 12 in the valve 6,1annular groove 13 and passages 11i. 'lhe pressure fiui d thus admitted drives the piston 8 forward, the piston chamber forward of the piston exhausting through a passage comprising theport 15, passage 16, passage 16, chamber 17, passages 18, annular chamber 19 and exhaust ports 20. The valve G is hele in its rear position by the pressure fluid act-ing against theforward end 33 of the valve. l

As the piston approaches the forward end of the piston chamber, pressure fluid is admitted to the chamber 28 and to the forward end of the'piston chamber by the groove 21 in the piston establishing communication between the port 23 and the ports 24 and 30. rlhus the 'fluid entering throughout lreaches t pressure fluid, fed constantly tothe port 23 through the inlet port 26 and the passage 25 is permitted to enter thechamber 28 through the port 2e and passage 27, to move the valve forward. The. pressure' fluid entering port 30 from Ythe groove f2.1 passes through the passage 31 and port 32 to the forward end of the piston'chan'iber? to return the piston, the port 3()v being so positioned that the motive i he forward end of the piston chamber to drive the piston rearwardly immediately upon the impact of the piston von the tool 9. rlhu's no ne lost in starting the piston on its return strolre, the ports 23, 2s and 30 and the groove 21 being positioned so that the valve 6 moves forward practically sinmltaneously with the entrance of the pressure fiuid'to return the piston. VAs the pressure fluid admitted through the'port 32 is practically at supply line pressure, a strong initial force Yis exerted on the piston to start it on its return stroke.

Because of this large initial force'exerted on the piston, it is not necessary to admit pressure'fluid through the entire return stroke, but rather it is possible to cut-off the supply after the piston has returned but a short distance, the piston being then driven through the remainder of the stroke bythe expansion of the pressure fluid already admitted as well as by its own momentum. Y

1t will be seen that on its return stroke the piston closes the ports 23, 2li and 30, thereby cutting off the supply of pressure fluid to theV passage 27, chamber 28 and the forward end of the piston chamber, and entrappingy the pressure fluid already admitted to said passage and chambers. The entrapped fluid in chamber 23V exerts a force on the fiange 29 to hold the valve in its forward position against the constantforce exerted by the pressure fluid on the end 33 of the valve.V The eXpansion of the pressure `fluidentrapped in the :forward portion of the piston chamber continues to drive the piston rearward, the pressure fluid tothe rear ofthe piston exhausting as hereinbefore mentioned. VUpon further movement on the ret-urn stroke, the piston uncovers the. ports 34andy 35 thus eX- hausting the piston Vchamber forward of the piston and alsothe chamber 28, the chamber 28 exhausting through-thefpassage 27 and port 35 into the forward end of the piston chamber 7 which in turn exhausts through the port 311, passage 36, annular chamber 19 and exhaust ports 20. Upon the exhaust of the chamber 28 t-he force exerted on the flange 29 is reduced whereupon the pressure fluid in the annular groove 26 acting on the end 33 of the valve vforces the valve rearwardly. The piston which has Vcontinuedin its rearward movement due to its own momentum after the exhaustion of the forward portion of the piston chamber, is then subjected to the influx of pressure fluid through the passage 14 atthe rear of the piston chamber, and is again driven forward.

We claim as our invention:

l. A pressure Huid operated tool having, in combination, a barrel forming a piston chamber, a piston reciprocable in said chamber and having a circumferential groove, a hollow reciprocable valve having a passage extending axially therethrough, and means for supplying pressure fluid to the forward end of said piston chamber comprising the passage through said valve, a passage in said barrel opening at its forward end into said piston chamber at a point intermediate the ends of the pist-on chamber, and a second passage in said barrel communicating at its rear end with said piston chamber at a point adjacent to the forward end lof said first mentioned passage, said second passage at its forward end opening into the forward end of the piston chamber, said circumferential groove being adapted to connect said passages when the piston is at the forward end of the piston chamber.

2. A pressure fiuid operated tool having, in combination, a barrel forming a piston chamber, a piston reciprocable in said chamber, a reciprocable hollow valve having a. pressure fluid passage therethrough, and means for supplying pressure fluid to the forward end of said piston chamber comprising the passage through said valve, two separate passages extending longitudinalh7 in said barrel and opening at their adjacent ends into said piston chamber at a point intermediate the ends of said chamber, said piston being shaped to provide a connection between said ends of said passages when the piston is at the forward end of the piston chamber.

n testimony whereof we have hereunto affixed our signatures.

ERNEST H. SHAFF. GOTTLIEB BRIEGEL. 

